A function that returns the distance between a point in space to a mathematically/algorithmically defined surface (called an implicit surface). This allows algorithms like raymarching and marching cubes to efficiently render complex 3D surfaces in 2D.

SDFs are increasingly commonly used in computer art, where defining an SDF that describes a large 3D scene entirely in a single pixel shader allows the code to be ran entirely on the GPU.

Articles:

• Signed distance function on Wikipedia
• Distance functions (GLSL)
• Ray Marching and Signed Distance Functions by Jamie Wong

Notable open-source libraries:

• hg_sdf (GLSL)

Videos:

• How to Create Content with Signed Distance Functions by Johann Korndörfer